Underwater sonic depth steering system



Dec. 6, 1960 4 c. K. sTEDMAN 2,962,997

UNDERWATEE SONIC DEPTH STEERING SYSTEM Filed April 3, 1946 2 Sheets-Sheet l o o V F' o l W Y V: T 3., s t s E NX n DLU O Y INVENTOR 6fm, if. STEQEEEN Ef /z/@w Dec. 6, 1960 c. K. s'rEDMAN 2,962,997

UNDERWTER SONIC DEPTH STEERING SYSTEM Filed April s, 194e 2 sheets-sheet 2 SERVO FIG. 4

Vertical Parpendicu/a( fa forpada ax s NNUU INVENTOR @56M Af. SYEMN ATTORNEY UNDERWATER SONIC DEPTH STEERING SYSTEM Cecil K. Stedman, Seattle, Wash., assigner to the United States of America as represented by the Secretary of the Navy Filed Apr. 3, 1946, Ser. No. 659,397

Claims. (Cl. 114-25) This invention relates to control systems, and particularly to improved means adapted to effect controlled mechanical movement of a desired object in a continuous and supervisory manner, under the influence of a plurality of controlling factors, the arrangement being such that all of said controlling factors are integrated in a predetermined manner and an infinite range of adjustments of the controlled object is achieved.

An important object of the invention is to provide such a controlling system which is particularly adapted to regulate the depth steering mechanism of underwater torpedoes and which provides hydrostatic depth steering modified by other controlling factors in a desired manner.

Another important object of the invention is to provide such improved controlling means which is electrically operated, but which eliminates all sliding electrical contacts and other mechanical friction such as might interfere with the accuracy and sensitivity of response of the mechanism.

Another object of the invention is to provide improved controlling means adapted for use in torpedo steering mechanisms of the general character described in my copending application, filed jointly with Harvey Brooks, under date of September l1, 1943, Serial No. 502,075, the present development affording improved, more accurate control of depth.

Still another object is to provide controlling means constituting an improvement upon the inventions disclosed in the copending applications of Lincoln K. Davis, Serial Nos. 502,070 (now Patent No. 2,472,369) and 502,071 (now Patent No. 2,903,665), both filed under date of September l1, 1943, the present invention eliminating the unavoidable friction inherent in the constructions of said Davis inventions.

Other objects and advantages will be apparent upon consideration of the present disclosure in its entirety.

In the drawings:

Fig. 1 is a schematic diagram of a control system constructed in accordance with the present invention.

Fig. 2 is a force diagram of the mechanical components of the system of Fig. 1.

Fig. 3 is a diagrammatic side elevational view of a somewhat modified arrangement.

Fig. 4 is a schematic diagram of a differential amplifier employed in conjunction with the embodiment of Fig. 3.

Referring now to the drawings, it is to be noted that the control system herein disclosed, although particularly adapted to be used in controlling the depth steering of torpedoes, is equally usable wherever it is desired to provide a very sensitive, accurate, quick-acting control system, the functioning of which is to be governed by a plurality of supervisory factors. When employed in controlling the depth steering of torpedoes, it is also to be noted that the mechanism herein described may be inter-related with acoustically responsive steering mechanism constructed in accordance with the copending application first above mentioned, and adapted to automatiarent cally control the movements of the torpedo either in depth, in azimuth, or both in response to the sound emanating from a target. Alternatively, the present apparatus is usable to control the depth steering of torpedoes generally, without regard to the presence of acoustic controls or other special automatic guiding means.

Reference character F designates a pendulous iron core of inverted U-shape, its bight portion being pivoted at P. Series connected excitation windings AC are carried by depending legs of the core, together with an additional coil E. The poles of the core are bridged by the horizontal core piece X, whichis spaced from the ends ofY the poles and laterally slideable with respect thereto. Two coils, C and D, are wound upon the slideable core piece X, and the assembly consisting of element X together with the coils C and D, is laterally movable by the depth steering rudder R which is connected to core piece X by linkage L. When the rudder is centered and the pendulous core F is in its normal position of rest, coils C, D are centered, one under each of the poles of core F. Also connected to the core F by a rod or stem S is a hydrostatic bellows B, mounted in a chamber CH. An orice O admits sea water to the chamber. By virtue of this arrangement, the hydrostatic pressure on the bellows influences the angular position of the core F with respect to the torpedo or support, the angular position of the core being thus dependent upon the depth of the assembly and the effect of gravity.

The coils C and D are so arranged that when the parts are in their normal positions of rest, with the rudder centered, equal voltages are induced in the coils C and D, while relative lateral movement of the coils with respect to the poles of core piece F (whether caused by movement of F or X), tends to increase the voltage induced in one coil and decrease that induced in the other, depending upon the direction of relative movement.

Coils C, D are connected to a differential rectifier RECT, which feeds the grid circuit of a control tube T whose output in turn governs the action of a servo assembly Z. The servo assembly activates a two-position relay Y, which controls the rudder-actuating motor M.

It will be understood that the bellows may be spring biased and/or adjustable to permit any desired depth setting, in one of the ways now known in the art. The torpedo or other controlled device will then seek the set depth, but any tendency to dive too sharply or deeply is opposed by the action of the pendulous core F and the rudder R.

The bellows, pendulum and rudder can be combined in a variety of ways, of which the foregoing is only one, although it will be appreciated that the disclosed arrangement is of a simple, easily constructed design from which friction is virtually eliminated, no sliding electrical contacts of any kind being used.

Depth setting may be effected electrically, rather than by mechanical adjustment of the bellows, by connecting a variable voltage from the coil E, adjustable by means of a potentiometer Sl, in series with C or D, as shown in Fig. l.

In the modified construction shown in Fig. 3, the pendulous core F is of closed form, except for the gap G. The bottom cross leg of the core thus projects transversely. The excitation coils AC' are wound upon the side legs of the core F', as in the embodiment previously described. The coil D is also carried directly by the pendulous core. The coil `C is mounted to move freely over the lower leg of the core F in the area bounded by the gap G, the diameter of the coil C being sucient to allow the core to swing freely. The form carrying the coil C' is mechanically linked to the bellows B and also to the rudder R', so that the coil is moved in and out of the gap by the action of the bellows and the rudder, whose actions are cumulative by reason of their connection in series in the manner shown.

The induced voltage in C increases as the coil is pushed further into the gap, and' when'it is in an intermediate position, equals the voltage in the coil D. The output of the differential rectifi'ei (shown in Fig. 4), in which the coils C', D are incorporated in the manner shown, is zero when the coil C is in the intermediate position, and goes plus or minus depending upon the direction of relative motion of the core and coil'. While the rectified output of the coil C could be balancedA against a D.C. bias rather than the rectified output from another coil, the latter arrangement makes the balance point independent of the excitationA voltage.

The action of the servo, in both embodiments, tends to maintain approximately fixed relative positioning of the core and coil.

Other basically equivalent arrangements might be employed in place of those above described. For example, the bellows alone might control the moving coil, While the rudder might move the point of support of the pendulum, or the coil could be used' as the pendulum, and the core be moved by bellows and rudder combined. All of these systems are basically equivalent, although its practical advantages make me prefer the embodiment first described.

The mechanics ofthe system of Fig. l can be derived with reference to the diagram of Fig. 2.

=angle of pitch in radians (nose down is positive) =inclination of pendulum relative to torpedo in radians (toward the nose is positive) x=displacement of bellows from their position when the torpedo is level at the running depth (positive as shown) Fozvalue of F in rounds at the running depth A=effective area of bellows or diaphragm -in sq. in.

S=stiffness of bellow alone in lb. per inchv h=increment of depth in ft.

W=the mass of the pendulumin slugs and a=V(-0) l, L and x are measured in inches An equation of equilibrium may be derived by balancing the moments acting on the pendulum about its pivot. Since it is well known that for small angles, especially angles less than 4, the sine andthe tangent of the angle is substantially numerically equal to the angle as expressed in radians. The angle designated as' et in Fig. 2 of the drawings is equal to the angle lia-0, therefore W(-0) is the resultant force acting normal to the moment arm L. This force when multiplied by this moment arm L is equal to. the moment about pivot P. At equilibrium this moment must be' balanced by a counter-moment acting on the pendulum. This `countermoment is the force acting at point P which force has a moment arm l. This force is made up of the natural stiffness of the bellows and the resultant hydraulic force. 'I'he force that results from the natural stiffness of the bellows is equal to Sl (the stiffness of the bellows in pounds per inch) multiplied by X which is the distance which the bellows has moved. The resultant hydraulic force is by definition the quantity (F0-F); In order to balance moments these forces are multiplied by the momentarml. Accordingly, thev equation for equilibrium is For small angles the distance X is equal to the arc 0l. yIhesubstitution of 0l for X in Equation 1l resultsY in the following:

Let the factor by which the pendulum swing is reduced as a result of the bellows stiffness be R, then from (3) 0 1 WL SI2 zii WL+ SI2 or vT/: 3* 1 (7) The flexibility of the bellows alone is:

Y AZZ l inches A/S* WL(R- 1) oggmlz- 1) 11a/Sq. in. (8)

The travel of the bellows is l0 or, from Equationsv 4, 6 and 7,

.454m WLl S12 The travel of the endvof the pendulum is L/ l times (9) or l .0176R-K inches per foot (9) L .0176R- niches per foot In a torpedo which may be considered by way of example, K=3.0. Therefore Equations 6,- 8, 9 and l0 become Travel of end of pendulun'1='.0059l inches per foot Equations l1 to 14 inclusive are in a form convenient for the design of a device of the kind illustrated in Fig. l. There are no hard and fastrequirementsV to be met, but there are reasonable limitations' on' the various constants. Backlash in the' swivel where the bellows connect with the pendulum cannot be much less than 0.0005 inch and should not correspond to more than half a' foot depth, hence from Equation' 13 For maximum sensitivity Equation 14 shows that we require L to be large and R small. The limit on L is set by compactne'ss of design. Very little sensitivity is gained by making R less than 1.25 and the' bellows ilexibility, Equation 12, becomes excessive. Accordingl l have chosen R=1.3 and L=2.5 inches, and it follows from Equation l5 that l=.22 inch. The only remaining factor is A and itis evident fromEquation l1 that in order to reduce the weight of the pendulum to a minimum, A should be as small asv possible. Ontheother hand, for a given flexibility there is a'lower limit to the bellows length so that yif the diameter is to'o small the bellows becomes unstable. A Sylphon of 0.31 square inch effective yarea hasbeen selected and the' required pendulumweight at 215 inches is' J2.1 lbs.-` Actuallyy the pe'ndulum'bob" can extend below the bottom of the core and be made proportionally lighter.

As shown in Fig. 1, switching means as Q' may be used to enable substituting for the manually adjustable depth setting potentiometer Q, an automatic acoustically responsive depth-controlling mechanism corresponding to that disclosed in the copending application first above mentioned. The acoustically responsive depth-controlling mechanism is shown in block diagram form and so marked, the microphone being designated M. Azimuth steering means is also indicated in block form, together with microphone Ma. It will be understood that these elements constitute no part of my present invention. When the switch Q is open and switch Q closed, the acoustic control is rendered effective, while straight depth control without the acoustic action may be achieved by opening. the switching means Q and closing the switch Q.

I claim:

1. Automatic depth steering apparatus comprising a depth rudder, a pendulous magnetic element, means for exciting said element, means including an inductance element arranged to be inuenced by pendulous movement of said magnetic element, mechanical connection between said rudder and one of said elements, and depth responsive means connected to and inuencing the mechanical movement of one of said elements, rudder driving means, and means responsive to the voltage induced in said inductance element for controlling the action of said rudder driving means.

2. Automatic depth steering apparatus comprising a depth rudder, a pendulous magnetic element, means including a mechanically movable inductance element arranged to be iniiuenced by pendulous movement of said magnetic element, means providing mechanical connection between said rudder and one of said elements and tending to move such element in response to movement of the rudder, depth responsive means connected to one of said elements and tending to move the same in response to changes of depth, motor means for driving said rudder, and electronic means connected to and controllable by said inductance element and arranged to control the action of said motor means.

3. Automatic depth steering apparatus comprising a depth rudder, pendulous magnetic means, mechanically movable inductance means arranged to be inuenced by pendulous movement of said magnetic means, said rudder being mechanically connected to and tending to move at least one of said means, depth responsive means connected to and tending to move at least one of said means in response to changes of depth, motor means for driving said rudder, and electronic relay means connected to and controllable by said inductance means and arranged to control the action of said motor means.

4. Apparatus as set forth in claim 3 in which said inductance means includes a pair of inductance elements, said magnetic means including a pair of coacting portions, and exciting means for said magnetic means, said inductance elements and coacting portions being so arranged that equivalent voltages are induced in said inductance elements when the parts are in a predetermined relative positioning, said electronic relay means including a diierential rectifier.

5. Automatic depth steering apparatus comprising a depth rudder, a pair of pendulous magnetic portions, a pair of mechanically movable inductance portions magnetically linked with respect to said magnetic portions, said rudder being mechanically connected to and tending to move at least one of said portions, depth responsive means connected to and tending to move at least one of said portions in response to changes of depth, motor means for driving said rudder, said magnetic and inductance portions being so arranged that equivalent voltages are induced in said inductance portions when said portions are in an intermediate position with relation to one another, said portions being movable in either direction with respect to one another from said intermediate position o-t change the voltages in said inductance portions in opposite directions, and means for controlling said motor means including a differential rectifier having an input, said inductance portions being connected to said input.

6. Apparatus as set forth in claim 5 in which said magnetic portions comprise a core of substantially inverted U-shape, means pivotally supporting the bight portion of the same, excitation windings carried by the legs of said core, said inductance portions being located adiacent and spaced conformably to the poles of said core. and common supporting means for said inductance portions whereby the same may be moved as a unit.

7. Apparatus as set forth in claim 5 in which said magnetic portions comprise a core of magnetic material mounted for pivotal movement, excitation meanscarried by said core, said inductance portions being located adjacent said core, said rudder being connected to said inductance portions and arranged to move the same simultaneously, and said depth responsive means being connected to said core to move the same about its pivotal support.

8. Automatic depth steering apparatus comprising a core of magnetic material pivotally suspended to form a pendulum, exictation means for said core, an inductance carried by said core, a second inductance mechanically movable with respect to the core and located adjacent the same to be influenced by relative movement between the core and said second inductance, rudder means and depth responsive means so mechanically connected as to move said second inductance with respect to said core, motor means for driving said rudder means, said core and inductances being so arranged that equivalent voltages are induced in the inductances when said core and second inductance are in an intermediate relative positioning, said core and second inductance being movable in either direction with respect to one another from said intermediate position to change the voltages in said inductances in opposite directions, and means for controlling said motor means including a differential rectifier having an input, said inductances being connected to said input.

9. Apparatus as set forth in claim 8 in which said depth responsive means comprises a bellows expansible and contractable under changes of pressure resulting from differences of depth and mounted for bodily movement in the line of its expansion and contraction, said bellows forming a link of a mechanical connection systern connecting the rudder means to the second inductance, whereby the eiects of the bellows and of rudder movement are additive.

10. Automatic depth steering apparatus comprising core means formed of magnetic material and pivotally suspended to form a pendulum, excitation means for said core means, inductance means coupled to said core means, whereby the current induced in said inductance is adapted to be changed by relative movement between the core means and inductance means, a rudder element, `a depth responsive element, said rudder element being connected to said inductance means, said depth responsive element comprising a pressure-operable member connected to the core to swing the same in response to changes of depth, and rudder operating means controllable in response to changes of induced voltage in said inductance means, whereby relative movement between said core means and inductance means may be caused under the inuence of either or both of said elements, or one of said elements may offset the action of the other.

Sperry May 17, 1921 Minorsky Oct. 15, 1935 

